Should someone point out that a 74 era 350 probably doesnt make any more power than the stovebolt 6? Personally I love seeing trucks with inline 6's at car shows...cuz there arent any. Heads and cam? Eh hell Modified vortec style heads and a 268H? Go with a small cap HEI or pertronix ignitor 2 or 3 conversion. Par for the course PM AirGap style intake as well... It will be lost in a sea of like trucks. Enjoy it in good health; take a good look at your front suspension when you yank the motor. I have no idea if there are any suspension differences between the stovebolt and the V8.
a 250hp inliner with a split manifold would be cool...put a T5 behind it